Such articles are intended to be worn inside a pair of conventional underpants or panties, and are placed in the crotch of the underpants. The article is normally secured to the underpants with the aid of beads of pressure-responsive adhesive provided on the article.
One particularly serious problem with known articles of this kind is that they have an unacceptable high leakage frequency. In the case of sanitary napkins and panty protectors, such leakage can result in discolouration or total spoiling of the clothes worn by the person concerned, in addition to the physical discomfort that such leakage causes.
Normally, leakage occurs at the long side edges of the article. The reason for this is that such articles, as distinct from children's diapers or diapers for persons who suffer from heavy incontinence, must be configured with a relatively small width, in order for the article to fit in the space between the user's thighs. Liquid which impinges on and is absorbed by the article spreads in the article at essentially the same speed in all directions around the wetting point. Since such absorbent products as sanitary napkins and the like normally have an elongated rectangular shape, the liquid absorbed by the article will reach the side edges thereof long before the absorbency of the end parts of the article is utilized.
Another reason for side leakage with articles of this kind is that the article is heavily deformed in use. This deformation is most pronounced within those parts of the article that are located between the thighs of the wearer and thus subjected to mechanical forces by the wearer's thighs. This results in a further reduction in the width of the article within precisely that region which is intended to initially capture body fluid secreted by the wearer. Leakage may also occur because the article has been initially positioned wrongly inside the underpants, or because the article has moved to a wrong position in use.
One method of reducing the risk of leakage with sanitary napkins and the like is to compensate for the narrow width of the article in the crotch part of the wearer by heavily overdimensioning the absorbency of the article. This will also reduce, to some extent, the risk of leakage should the article be positioned wrongly in the underpants of the wearer.
However, this does not provide a wholly successful solution to the leakage problem. Absorbent articles of the kind meant here are normally provided with a cellulose-fluff absorbent pad, since fluff is a relatively cheap raw material and because it can be handled with well-tried manufacturing techniques. The primary drawback with the use of fluff as an absorption material is that its absorbency per unit of volume is relatively low. Consequently, products which are produced from cellulose fluff become, of necessity, thicker and more clumsy the greater the desired absorption capacity.
Articles such as sanitary napkins, panty protectors and guards for people suffering light incontinence are intended to be worn by adult, often healthy and working people. Consequently, it is required by the users that such articles will not be noticed when worn beneath conventional clothes, but which will nevertheless be leakage-proof. The article shall also be comfortable to wear and shall not chafe or otherwise irritate the skin of the wearer. In this respect, it is important that the surface of the article located nearest the wearer's skin will remain as dry as possible, even after absorbing body liquid. This cannot be achieved easily, particularly when the absorbent article is a sanitary napkin, since menstruation blood has a high viscosity and therefore tends to adhere to the surface of the napkin. So-called re-wetting is another problem which is particularly pronounced in both sanitary napkins and incontinence guards. Re-wetting means that body fluid which has already been absorbed by the absorbent pad is pressed by external forces back towards the skin of the wearer, for instance when the wearer sits down.